6-acetyl-1, 1, 2, 4, 4, 7-hexamethyl-1, 2, 3, 4, tetrahydronaphthalene



United States Patent 3,045,047 6-ACETYL-1,1,2,4,4,7-HEXAlVlETHYL-1,2,3,4, TETRAHYDRONAPHTHALENE David Davidson, New York, N.Y., and Robert M. Lusskin, Haworth, N.J., assignors, by mesne assignments, to The Truhek Laboratories, 1110., East Rutherford,

N .J., a corporation of Delaware No Drawing. Filed Aug. 31, 1954, Ser. No. 453,428 1 Claim. (Cl. 260592) This invention relates to a new class of chemical com pounds adapted for use as fixatives and ,blending agents in the manufacture of perfumes and perfumed products. These compounds are acylpolyalkyl-l,2,3,4-tetrahydronaphthalenes and most of them have a pronounced musklike odor.

Compounds possessing an odor of musk are valuable in perfumery for their marked fixative and blending properties. Among these, the mostvaluable are the macrocyclic musks, that is organic compounds containing 15 to 18 atoms in an alicyclic ring. Examples of such compounds are muscone, civetone, pentadecanolide, and ethylene brassylate. However, these macrocyclic compounds :are not readily available because either they must be extracted from diflicultly accessible natural sources or they must be synthesized by complicated chemical processes.

Other products which are known as nitro musks are polynitrated aromatic compounds, and also possess musklike odors. The manufacture of nitro musks is relatively uncomplicated. Consequently, they are inexpensive, but the quality of their odor is harsh and therefore they are not as desirable as the macrocyclic musks.

We have discovered a class of non-nitrated compounds which are not macrocyclic but which possess valuable musk-like odors quite as line as those of the macrocyclic compounds themselves. It is surprising that compounds unrelated chemically to the macrocyclic musks should possess odors so similar to them. Moreover, these new compounds are synthesized readily from commercially available, inexpensive raw materials.

These compounds are acyl derivatives of 1,2,3,4-tetrahydronaphtha'lene in which at least two carbon atoms in the alicyclic ring of the nucleus are quaternary carbon atoms in that they have two alkyl groups attached thereto. Those compounds which have been found to possess the most pronounced musk-like odor have two methyl groups attached to the carbon atoms located in the positions 1 and 4 of the alicyclic ring. Further, the preferred compounds have the acyl group attached to the carbon atom in position 6 in the aromatic ring of the nucleus, although because of the isomeric and sometimes symmetrical nature of many of these compounds, the positions 6 and 7 are generally equivalent. In addition, both the alicyclic and aromatic rings may be further substituted by alkyl groups containing one to three carbon atoms. This class of compounds may therefore be represented by the following general formula moo 6 R0 l R2 8 1 2 R:

3,045,047. Patented July 17, 1962 The presence of two quaternary carbons in the alicyclic portion of the molecule appears to be necessary for the production of a musk-like odor. Thus the acetyl-1,1-di-- nitrated compounds which possess musk-like odors similar to the macrocyclic musks.

A further object of the invention is to provide acylpolyalkyl-1,2,3,4-tetrahydronaphthalene derivatives containing two quarternary carbon atoms and possessing musk-like odors.

A specific object of the invention is to provide a new class of compounds consisting of acylpolyalkyl-1,2,3,4- tetrahydronaphthalenes containing two quaternary carbon atoms in the positions 1 and 4 of the alicyclic ring of the nucleus and in which the alkyl groups of the compound contain from one to three carbon atoms.

These and other objects and features of the present invention will appear from the following description thereof wherein reference is made to specific compounds of the class of acylpoly-alkyl-1,2,3,4-tetrahydronaphthalenes which possess musk-like odors, a suflicient number of compounds being particularly described to indicate the common characteristics of the compounds embraced within the class to which this invention relates.

The compounds of the present invention may be prepared in any suitable way, as, for example, by acylating the alkyl-1,2,3,4-tetrahydronaphthalenes by means of a suitable catalyst and thereafter isolating and purifying the alkylated acyl compounds. Typical procedures for this acylation are given in the examples below.

The polyalkyl l,2,3,4 -tetrahydronaphthalenes employed for the acylation may be represented by formula wherein R,,, R,,, R R are alkyl radicals selected from the group consisting of methyl and ethyl; R R R R R and R are selected from the group consisting of hydrogen, methyl, ethyl, propyl, and isopropyl.-

T-hese polyalkyl l,'2,3,4 tetrahydronaphthalenes may be prepared from appropriately substituted monocyclic hydrocarbons such as a 2,5-dichloro-2,5-dialkylhexane derivative, and particularly, 2,5-dichloro-2,5-dimethylhexane when R,,, R R R are methyl. A typical method which may be used is that wherein aluminum chloride is employed as a catalyst in accordance with the procedure described by Bruson and Kroeger in the Journal of the American Chemical Society, vol. 62, pp. 36-44 1940).

Bruson and Kroegerhave described the preparation and properties of l,1,4,4-ttetramethyl-1,2,3,4-tetuahydronaphthalene and 1,1,4,4, 6-pentamethyl 1,2,3,4 tetrahydronaphthalene. The compound 1,1,4,4-tetramet.hyl-6- ethyl-1,2,3,4-tetrahydronaphthalene was prepared from ethylbenzene, 2,5 dichloro 2,5 dimethyl-hexane, and aluminum chloride.

The 1,1,4,4-tetraalkyl 1,2,3,4 tetrahydronaphthalenes substituted with alkyl groups at position 2 or 3 of the alicyclic ring, as well as on the aromatic ring, were prepared by the cyclodehydration of the appropriately substituted alcohols where the R groups have the same significance as in the preceding formula.

These alcohols themselves may be prepared by any suitable method, as, for example, by a Grignard reaction. The procedure employed for the cyclodehydration was that described by Roblin, Davidson and Bogert, in the Journal of the American Chemical Society, vol. 57, pp.

1,2,3,4 tetrahydronaphthalenes not previously described, but which have now been prepared using the general process either of Bruson and Kroeger or of Rob lin, Davidson and Bogert, are the following:

Acylated compounds of the present invention may be derived from the foregoing or other similar polyalkyl- 1,2,3,4-tetrahydronaphthalenes by methods such as those employed in the following typical examples.

Example I .6-Acetyl-1,1,2,4,4,7-Hexamethyl- 1,2,3,4-Tetrahydranaphthalene To a solution of 12.0 g. (0.055 M) 1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene and 5.5 g. (0.070 M) acetyl chloride were added'in minutes at 0-5 C., 12.0 gms. (0.07 M) anhydrous ferric chloride. The temperature was raised slowly to 25 C., then mixed 1 hour at 25. One hundred cubic centimeters of cold water and 100 cc. benzene were added. The oil layer was first washed with aqueous salt solution then aqueous sodium carbonate solution. After removing the benzene by distillation, the crude product was fractionated to obtain 6.9 g. (43%) of 6-acetyl-1,1,2,4,4,7-hexamethyl-1,2,3,4- tetrahydronaphthalene with a powerful odor of musk reminiscent of the macrocyclie musks. The boiling point of the product was 150 at 2 mm. and the refractive index was 1.5350 at C.

Example 2 .6-Pr0pi0ny l-] ,1 ,4,4-Tetramethyl-7- Ethyl-1,2,3,4-Tetrahydronaphzhalene To a solution of 43.2 g. (0.2 M) 1,1,4,4-tetrarnethyl- 6-ethyl-1,2,3,4tetrahydronaphthalene, 50.0 g. ethylene dichloride, and 19.9 g. (0.215 M) propionyl chloride, were added 30.2 g. (0.226 M) aluminum chloride over a period of two hours at 05 C. The temperature was raised slowly to and then the reaction was mixed 1% hours at 25. Dilute hydrochloric acid was added and the oil layer was washed first with aqueous salt solution, then with aqueous salt solution containing sodium carbonate. The ethylene dichloride was removed by distillation and the distilled product, which boiled at 160 at 5 mm. was crystallized from aqueous methanol. The recrystallized 6 propionyl 1,1,4,4 tetramethyl-7-ethyl- 1,2,3,4-tetrahydronaphthalene melted at 46-48" and had a fine odor of musk.

Example 3 .6-A cetyl-1,1,4,4-Tetramethyl-7-Ethyl- 1,2,3,4-Tetrahydronaphthalene To a solution of 400 g. (1.85 M) 1,1,4,4-tetramethyl- 6-ethyl-1,2,3,4-tetrahydronaphthalene and 167 g. (2.13 M) acetyl chloride were added 295 g. (2.24 M) aluminum chloride powder in 3 hours. The reaction mixture was allowed to rise to room temperature overnight and then benzene and dilute hydrochloric acid were added. The oil layer was washed with 500 cc. portions of aqueous salt solution and sodium carbonate solution. After the crude product was fractionated at at 2 mm. it was crystallized from aqueous methanol to obtain purified 6-acety1-1,1,4,4-tetramethyl-7-ethyl 1,2,3,4 tetrahydronaphthalene (M.P.=46.5), with a fine, persistent musklike odor.

Example 4.-6-Isobutyryl-1,1,4,4-Tetramethyl-7- Etltyl-1,2,3,4-Tetrahydr0naphthalene The procedure of Example 3 was followed with 43.2 g. 1,1,4,4 tetramethyl 6 ethyl-1,2,3,4-tetrahydronaphrtbalene, 24.5 g. isobutyroyl chloride, and 32 g. aluminum chloride. The purified fi-isobutyryl-l,1,4,4tetramethyl-7-ethyl-1,2,3,4-tetrahydronaphthalene melted at 61 and had a pleasant odor resembling that of musk.

Other acylpolyalkyltetralins prepared by the general procedures of Examples 1, 2 and 3 are as follows:

The quality, intensity and persistency of the odors of the present compounds cited by way of example above varies considerably although all appear to have valuable properties as fixatives and blending agents in the manufacture of perfumes and perfumed products.

While numerous compounds have been mentioned above and typical methods of procedure for their production have been described, it will be apparent that other membersof the class of acylpolyalkyl-1,2,3,4-tetrahydronaphthalenes may be produced and other methods for their production may be employed. In view thereof, it should be understood that the particular compounds and methods of procedure described should be understood to be illustrative only and are not intended to limit the scope of the invention.

What we claim is:

6-acetyl-1,1,2,4,4,7-hexamethyl 1,2,3,4 tetrahydronaphthalene.

References Cited in the file of this patent UNITED STATES PATENTS 2,897,237 Carpenter et al. July 28, 1 959 

